Generally, systems for capturing the movement of a solid have applications in various fields such as health, multimedia or geophysics.
For video or video game applications, the movements of a user can be used to control virtual reality systems. As an example, the movements of a player may be recorded to control the movement of a virtual character in a synthetic scene.
In the field of portable electronics, movement capture devices enable the appliances to be adapted to the usage context. They make it possible, for example, to optimize the reception of a portable telephone by determining its orientation, or to enhance the interfaces of personal digital assistants.
Regarding the field of health, such systems can be used to position surgical tools, or to monitor the movements of elderly people or people who have health problems causing reduced mobility.
The movement sensors, and more specifically the angular position sensors, are greatly miniaturized and are the subject of research to give them a robustness and a cost that are compatible with applications aimed at the general public.
The position of a solid in space is entirely determined by establishing six quantities. Among these, three quantities can be distinguished that are likely to reflect translation movements and three other quantities likely to reflect rotation movements. The latter three quantities correspond to angular positions, called attitude angles, that can be used to determine movements. Furthermore, a rotation can be defined by a quaternion.
For example, the document FR 2 838 185 (Atomic Energy Commission) discloses a device for capturing the orientation of a solid comprising at least one angular position sensor likely to be made integral with the solid and to deliver at least one measurement datum representing the orientation of the solid, a means generating test data representing an estimated orientation of the solid, and a means for modifying the estimated orientation of the solid by comparing the measurement datum and test data. After one or more modifications of the estimated orientation, the latter converges toward the actual orientation of the solid, or, more specifically, toward the measured orientation. This device does not require any calculation means to establish the orientation or the inclination of the solid on the basis of a function of the sensor measurement data, and makes it possible to dispense with their nonlinear behaviors.
However, such a device requires numerous calculations and cannot, or can only with difficulty, be embedded on a system of reduced size. Such a device is also sensitive to the specific acceleration of the solid.
Therefore, the present invention aims to resolve the problems mentioned previously.